This commit lays the groundwork for the new editor by adding empty files to the assets in order to change them later on. The new editor is not stable enough to be merged right now, but delaying it to 15.0 would be problematic as the current editor has many bugs that we are unable to fix because of how summernote interacts with browser-dependent code as well as all the hacks that were done on top of it for Odoo since 8.0.